TM 5-3895-374-24-1
TROUBLE
CAUSE
REMEDY
OVERLOAD RELAYS
1.
Sustained overload
1.
Check for excessive motor currents or current
unbalance.
2.
Loose or corroded connection in power
2 Clean and tighten
circuit.
3
Incorrect thermal units.
3
Thermal units should be replaced with correct
size for the application conditions.
Tripping
4
Excessive coil voltage.
4.
Voltage should not exceed 110% of coil rating.
1.
Incorrect thermal units
1.
Check thermal unit selection table Apply proper
thermal units.
2.
Mechanical binding, dirt. corrosion, etc.
2.
Replace relay and thermal units.
3.
Relay previously damaged by short cir-
3. Replace relay and thermal units.
cuit.
4.
Relay contact welded or not in series with 4
Check circuit for a fault and correct condition.
contactor coil.
Replace contact or entire relay as necessary.
MAGNETIC &
MECHANICAL PARTS
1.
Broken shading coil.
1.
Replace magnet and armature.
Noisy Magnet
2.
Dirt or rust on magnet laces.
2.
Clean.
3.
Low voltage.
3.
Check coil terminal voltage and voltage dips.
1.
No control voltage.
1.
Check and control circuit for loose connection or
poor continuity of contacts.
2.
Low voltage.
2.
Check coil terminal voltage and voltage dips
Failure to Pick-up and
during starting.
Seal
3.
Mechanical obstruction.
3.
WITH POWER OFF check for free movement of
contact and armature assembly.
4.
Coil open or overheated.
4.
Replace.
5.
Wrong coil.
5.
Replace.
1.
Gummy substance on pole faces.
1.
Clean pole faces.
2.
Voltage not removed.
2.
Check coil terminal voltage and control circuit.
Failure to Drop-Out
3.
Worn or corroded parts causing binding.
3.
Replace parts.
4.
Residual magnetism due to lack of airgap 4.
Replace magnet and armature.
In magnet path.
5.
Contacts welded.
5.
See "Contacts - Welding".
PNEUMATIC TIMERS
Erratic Timing
1.
Foreign matter in valve.
1.
Replace complete timing head or return timer to
factory for repair and adjustment.
Contacts Do Not Operate
1.Maladjustment of actuating screw.
1.
Adjust per instruction in service bulletin.
2.
Worn or broken ports in sn ap switch.
2.
Replace snap switch.
LIMIT SWITCHES
Broken Parts
1.
Overtravel of actuator.
1.
Use resilient actuator or operate within tolerances
of the device.
MANUAL STARTERS
Failure to Reset
1.
Latching mechanism worn or broken.
1.
Replace starter.
(Page 3-148)
